The patent literature is extensive on various features of electrochemical cell designs dealing with current collector designs, improvements of electrical conductivity and active material utilization as well as hydrogen gas generation in aqueous electrolyte sealed cells e.g. containing alkaline zinc electrodes or acidic lead electrodes. The prior art exclusively relies on all metal current collectors:
Winger in U.S. Pat. No. 3,069,485 (1962) describes the “brass-tongue” current collector riveted to the closure member used in various forms for many years in Union Carbide/Eveready alkaline cells.
Brys in U.S. Pat. No. 6,251,539 (2001) describes means of improving the performance of alkaline cells comprising a zinc anode and manganese dioxide cathode especially in high power application by the addition of electrically conductive powders such as tin, copper, silver, magnesium, indium or bismuth to the anode mixture. The conductive powders are in physical mixture with the zinc particles. A preferred electrically conductive powder is tin powder. The alkaline cells employing the conductive powders preferably contain no added mercury and preferably are also essentially free of lead.
Collien in U.S. Pat. No. 6,087,030 (2000) describes novel alkaline electrochemical cells having high drain capacities at voltages of at least 1.1 V for use in small appliances such as hearing aids. The anode includes potassium hydroxide, zinc powder, 0.02% to 0.5% of a reaction rate enabling compound selected from a compound of indium, cadmium, gallium, thallium, germanium, tin, or lead, with indium compounds being preferred. The anode material optionally further includes a low level of mercury, and preferably a surfactant comprising hydroxyethylcellulose. The cathode provides sufficient oxidative capability to oxidize the zinc at a sufficient rate to support the electrical drain demands on the cell. A cathode, in a preferred zinc-air cell for a hearing aid, includes at least 5 air ports, evenly distributed over the surface of the bottom of the cathode can.
Shinoda in U.S. Pat. No. 5,376,480 (1994) describes a gelled negative electrode for an alkaline battery without mercury enabling uniform dispersion of zinc or zinc alloy powder and an effective metal which can be one or more of an oxide or hydroxide of indium, lead, gallium, bismuth. The zinc or zinc alloy powder and the effective metal are dry mixed in advance of mixing with a gelled alkaline electrolyte. In order to obtain satisfactorily high vibration strength and impact resistance, fiber material can be added to the gel to form the negative electrode. The fiber material may be selected among Rayon, Vinylon, Acryl, Vinyon, polyamide, polypropylene, polyethylene, mercerized pulp, and linter pulp.
Daniel-Ivad in U.S. Pat. No. 5,626,988 (1997) describes zinc active powder for a mercury-free rechargeable electrochemical cell coated with a surfactant, and separately with an aqueous solution of indium sulfate. Without any subsequent filtering, washing or drying, the powder is employed in the anode gel of an electrochemical cell. The cell can include a hydrogen recombination catalyst in contact with the electrochemically active material of the cathode.
Tomantschger in U.S. Pat. No. 5,162,169 (1992) discloses a rechargeable or primary electrochemical cell in which hydrogen may evolve. The cell contains an auxiliary electrode material comprising manganese dioxide and a catalyst as the oxidant providing for the recombination of pressurized hydrogen at pressures ranging from substantially zero gauge pressure up to the relief pressure of the cell. The cell is a sealed cell having a manganese dioxide cathode, a zinc anode and aqueous electrolyte contacting both anode and cathode. The aqueous electrolyte may be alkaline or it may be ammonium chloride or zinc chloride, or mixtures thereof. Suitable catalysts include silver, platinum, silver oxide, or silver dioxide.